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1.
活化分析   总被引:1,自引:0,他引:1  
本文是《分析试验室》定期评述中“活化分析”的第6篇文章,它对我国活化分析领域在2003年6月-2005年12月的工作进展作了较全面的评述。内容包括活化分析方法学及其在生命科学、环境科学、地学和考古、国家安全等领域的应用,并展望了活化分析的发展趋势。  相似文献   

2.
Activation analysis in various modifications is one of the most frequently applied analytical methods for environmental research. The method is widely used for routine analysis but its specific approaches allow it to be used for very special research that can hardly be done by other methods. This review gives a brief survey of some examples.  相似文献   

3.
An activation analytical method is described for the determination of small concentrations of Ga in tungsten. The samples are irradiated with reactor neutrons and dissolved in a hot chamber using a remote manipulator. After the adjustment of thepH, Ga is extracted in the form of its cupferron complex in chloroform solution. The organic phase is washed and, depending on the efficiency of the separation from tunsgten, a Ge(Li) semiconductor detector, or a NaI(Tl) scintillation counter is used for the gamma-spectrometric evaluation. The sensitivity of the method for a sample of 2 g was found to be 10−9 g of Ga/g of W. The determination can be carried out, and is well reproducible, with an accuracy of ±30%.  相似文献   

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5.
Neutron-activation analysis has been applied to the determination of mercury in a variety of environmental samples (Table 11) and so far has played an important role in the environmental research concerned with mercury pollution. The virtues of this method as its high sensitivity, applicability to various samples make the method attractive. On the other hand the high cost, limited availability of irradiation facilities, the time consumming analysis (due to irradiation and cooling) are important drawbacks and limit the use of the method, particularly in routine work. With the development of flameless atomic absorption mercury determination is more and more carried out with the aid of the latter technique. It seems, however, that activation analysis will remain a reference method and an anchorage in the cases when other methods fail.  相似文献   

6.
A simple method for the radiochemical neutron activation analysis of bromine in rock samples is described. The irradiated samples are ignited in an induction furnace in a flow of air for four minutes. The bromine expelled is collected onto activated charcoal which is measured using a Ge(Li) detector. The yield of the chemical separation is 85–100% and the detection limit is 7 ppb. The method is discussed and results for the analysis of 14 USGS standard rock samples are presented.  相似文献   

7.
A method has been developed for the determination of trace quantities of mercury in biological samples, in which homogeneous irradiation was achieved by introducing a rotating irradiation disk facility in the reactor pool water, and possible loss of mercury during chemical processing was reduced by using a simple procedure. This procedure involved the destruction of the sample in a reflux system with conc. HNO3 or fuming HNO3+H2O2 and subsequent isolation of mercury by spontaneous deposition on Cu sieves from dilute HNO3(0.5–1.5N). The possibility of using Au or Co as standards, instead of mercury which is easily volatile, was also evaluated.  相似文献   

8.
Sensitivity curves for detecting any element/isotope with Z = 20 to Z = 90, through 1, 2 and 3 particles emission reactions, activated with protons, deuterons and alphas of up to 35 MeV energy have been estimated and presented in graphical form. From these curves the detection sensitivity of any element/isotope in the aforementioned range, in any given matrix, can be directly obtained for an infinitely thick, a moderately thick or even a thin target. Furthermore, these curves would also help in selecting the most suitable nuclear reaction for the measurement of a particular element or isotope in a given matrix, and would also provide an indication of the unwanted and interfering activities being produced simultaneously.  相似文献   

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10.
Different methods (-, - and X-ray spectrometry, activation analysis, mass spectrometry) are reviewed for129I determination in environmental samples. The sensitivities and the129I/127I ratios of the different methods are given. The influence of the127I(n, )128I(n, )129I(n, )130I reactions on129I determination by activation analysis has been studied. A chart of optimal sample irradiation conditions is given.  相似文献   

11.
The triple comparator method is used for the analysis of impurities of high purity silicon by neutron activation. The ratios of the specific photopeak activities of the isotopes investigated to the specific photopeak activities of the gold, indium and cobalt comparators were determined. The triple comparator method avoids some tedious problems in the multi-element activation analysis and it is very well suited for the determination of ‘non-expected’ elements. Research associate of the N. F. W. O.  相似文献   

12.
Activation methods are important because of their sensitivity. The accuracy and precision obtainable with charged-particle activation analysis (CPAA) have been significantly improved; the accuracy has been demonstrated in inter-laboratory and inter-method comparisons. The inherent complexity of CPAA makes it unsuitable for routine work, but the method is valuable for special applications, e.g., certification of reference materials, and for the determination of certain elements. Most applications concern the determination of light elements in metals and semi-conductor materials. After removal of surface layers by chemical etching, the concentrations of carbon, nitrogen and oxygen found by CPAA in some industrial metals, (e.g., aluminium, molybdenum and tungsten) proved to be orders of magnitude lower than expected from the results of other procedures. Other applications are the determination of medium- and high-Z elements, (e.g., calcium, cadmium, thallium and lead) in metals; these elements are very difficult to determine with neutron activation. Environmental powdered materials can be analyzed accurately; because of their low thermal conductivity, they must be irradiated under helium instead of vacuum to avoid volatilization of matrix components.  相似文献   

13.
Chromium at concentrations of parts per billion in water, may be determined by activation analysis using an instrumental method preceded by concentration on anion exchange resins. Blank runs, using deionized water, are carried through the steps of preconcentration. The blank-resin and sample-resin are irradiated together with thermal neutrons, and the gamma spectrum of each is stored in half of the memory unit of a multichannel analyzer. Subtraction of the blank-resin spectrum from the sample-resin spectrum gives the51Cr peak free from interfering activities.  相似文献   

14.
The method described in a previous work to separate trace amounts of selenium in organic samples without using a carrier, based on the adsorption on active carbon filters of the complex formed with ammonium pyrrolidindithiocarbamate (APDC) at pH 1.5–2, has been applied to urine samples from 15 females patients suffering from cervical uterine cancer. With this type of sample the method reaches a maximum sensitivity (few ppb) with a good statistical variation (±12%). Since the highest concentration of selenium in human tissues is found in the kidney, and the elimination of this element is mainly by the urine, the method seems to be a powerful tool in the research about the human metabolism of selenium. This paper shows a possible relation of selenium concentration in human urine and the evolution time of cervical uterine cancer, in spite of limits imposed by the statistical error plus the inhomogeneity of the sample.  相似文献   

15.
32P was separated from the irradiated silicon matrix as ammonium phosphomolybdate and the activity was measured with a GM tube or on a plastic scintillator. The second-order interference was taken into consideration. Research associate of the N.F.W.O.  相似文献   

16.
The principle and some applications of charged particle activation analysis are described. Important applications are the determination of light (B, C, N, O), medium (Ca, Fe) and heavy (Cd, Pb) elements in metals and semi-conductors and the analysis of geological and environmental materials.  相似文献   

17.
Summary Rib bones of Brazilian people were analyzed by neutron activation analysis to evaluate element composition. Freeze-dried cortical and trabecular tissues, separately, and calcinated total rib tissues were analyzed. The concentrations of the Ba, Br, Ca, Cl, Fe, K, Mg, Mn, Na, P, Rb, Sr, and Zn elements were determined. Comparisons between the results obtained in cortical and trabecular bones indicated significant differences in the concentration for several elements. Results obtained in cortical and trabecular bones were also compared with literature values.  相似文献   

18.
Although Neutron Activation Analysis is usually not very common in aerosol physics, there are fields of application which seem to be rather successful. In general it is shown which properties activable aerosols should have, how they can be produced and how aerosol samples might be drawn. By use of special aerosol separators not only the mass-concentration but also the size-distribution of the aerosol can be determinated. Based on two studies, the utility of activable aerosols is demonstrated: Calibration and test of a simple discontinously working aerosol monitor for the off-gass system of isotope hoods; dynamic o radioactive ionized aerosols in a sealed room. Finally a general survey of further applications of activable aerosols is given.  相似文献   

19.
A neutron activation method was developed for the determination of traces of mercury in high purity bismuth. After neutron irradiation at a flux of approx. 4.1011 n/cm2/sec, mercury was separated from the matrix by displacement on metallic copper and subsequent distillation and amalgamation on silver foil. The γ-activity of the 197Hg was counted in the 68–77 ke V region. The accuracy of the procedure was tested by an addition method of analysis. Bismuth samples with a mercury content in the 10 p.p.b. region were analysed.  相似文献   

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